Metal wiring method for an undercut

Abstract

A metal wiring method for an undercut in a MEMS packaging process includes disposing a MEMS element on a silicon substrate, welding a glass wafer to an upper portion of the silicon substrate having the MEMS element disposed thereon, the glass wafer having a hole formed therein for connecting a metal wiring, depositing a thin metal film for the metal wiring in the hole, and ion-mealing the deposited thin metal film. By the ion-mealing, the method is capable of connecting a metal wiring to a via hole having an undercut.

What is claimed is:  
     
       1. A metal wiring method for an undercut in a MEMS packaging process, the method comprising: 
       disposing a MEMS element on a silicon substrate;  
       welding a glass wafer to an upper portion of the silicon substrate having the MEMS element disposed thereon, the glass wafer having a hole formed therein for connecting a metal wiring;  
       depositing a thin metal film for the metal wiring in the hole; and  
       ion-mealing the deposited thin metal film.  
     
     
       2. The method as claimed in  claim 1 , wherein in the ion-mealing, the deposited thin metal film is resputtered by injecting accelerated gas particles to strike the deposited thin metal film. 
     
     
       3. The method as claimed in  claim 2 , wherein if the glass wafer has an undercut formed around the hole formed therein, the undercut is filled with the resputtered thin metal film. 
     
     
       4. The method as claimed in  claim 3 , wherein when the glass wafer has the undercut formed around the hole formed therein, the ion-mealing is performed until the undercut is removed. 
     
     
       5. The method as claimed in  claim 2 , wherein the accelerated gas particles are argon gas particles.